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Fizika i Tekhnika Poluprovodnikov, 2016, Volume 50, Issue 3, Pages 369–376
(Mi phts6518)
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This article is cited in 3 scientific papers (total in 3 papers)
Micro- and nanocrystalline, porous, composite semiconductors
Photoluminescence and confinement of excitons in disordered porous films
N. V. Bondar'a, M. S. Brodina, A. M. Brodinb, N. A. Matveevskayac a Institute of Physics, National Academy of Sciences of Ukraine, Kiev
b National Technical University of Ukraine "Kiev Polytechnic Institute"
c Institute for Single Crystals, National Academy of Sciences of Ukraine, Kharkov
Abstract:
The exciton confinement effect in quantum dots at the surface of SiO$_2$ spheres and the percolation phase transition in films based on a mixture of pure SiO$_2$ spheres and spheres covered by CdS quantum dots (SiO$_2$/CdS nanoparticles) are studied. It is found that, due to the high surface energy of spheres, the quantum dots deposited onto their surface are distorted, which modifies the exciton confinement effect: the effect is retained only in one direction, the direction normal to the surface of the spheres. As a result, the energy of the exciton ground state exhibits a complex dependence on both the quantum-dot radius and sphere size. In the optical spectra of films based on this mixture, the clustering of small-sized nanoparticles and then, at a critical concentration of nanoparticles of $\sim$60%, the formation of a percolation cluster are detected for the first time. The critical concentration is twice higher than the corresponding quantity given by the model of geometrical “colored percolation”, which is a consequence of interaction between submicrometer nanoparticles. The relation between the basic parameters of the percolation transition, such as the film porosity, coordination number, and the quantity defining the number of particles in the percolation cluster, is obtained and analyzed.
Keywords:
Percolation Threshold, Diffusive Reflectance Spectrum, Percolation Cluster, Percolation Transition, Exciton Ground State.
Received: 27.05.2015 Accepted: 14.07.2015
Citation:
N. V. Bondar', M. S. Brodin, A. M. Brodin, N. A. Matveevskaya, “Photoluminescence and confinement of excitons in disordered porous films”, Fizika i Tekhnika Poluprovodnikov, 50:3 (2016), 369–376; Semiconductors, 50:3 (2016), 364–371
Linking options:
https://www.mathnet.ru/eng/phts6518 https://www.mathnet.ru/eng/phts/v50/i3/p369
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